A complex Gaussian approach to molecular photoionization

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics
• Computational Chemistry

Background:

• Molecular photoionization is crucial for understanding molecular behavior.
• Accurate calculation of photoionization observables is computationally challenging.
• Existing methods often require complex numerical integrations.

Purpose of the Study:

• To develop a computationally efficient Gaussian approach for molecular photoionization.
• To accurately represent continuum wavefunctions using complex Gaussian-type orbitals (cGTOs).
• To analytically evaluate transition integrals for simplified calculations.

Main Methods:

• Nonlinear optimization to obtain optimal sets of complex Gaussian-type orbitals (cGTOs).
• Representation of radial wavefunctions for outgoing electrons using cGTO expansions.
• Time-independent partial wave approach to derive analytical transition integrals.

Main Results:

• Demonstrated the ability to accurately represent continuum wavefunctions.
• Achieved analytical evaluation of transition integrals in both length and velocity gauges.
• Successfully validated the Gaussian approach for NH3 and H2O photoionization.

Conclusions:

• The proposed Gaussian method provides an accurate and efficient strategy for molecular photoionization.
• Analytical integration significantly simplifies the numerical evaluation of photoionization observables.
• This approach offers a robust tool for theoretical studies in molecular photoionization.